recordinghacks

Microtech Gefell M 92.1 S

Cardioid Tube Condenser Microphone

The M92.1S is a large-diaphragm, fixed-cardioid tube mic built around the EF 86 pentode (in triode configuration). This is a single-pattern version of the UM 92.1 S.

Like its multipattern sibling, the M 92.1 S employs Gefell’s PVC-membrane M7 capsule. However, because this mic is a single-pattern mic, the rear membrane of the M7 capsule is not connected to the amplifier circuit.

US customers should be aware that all “.1” Gefell mics include RF/EM protection circuits required for CE compliance. Although US restrictions on electromagnetic radiation are less strict, Gefell does not currently provide US-only circuits.

According to Oliver Archut of TAB-Funkenwerk, these EMI protection circuits “choke” the sound and introduce phase shift. He has provided instructions for removing the EM/RF circuitry of the UM92.1S — which are presumably also applicable to the M92.1S. See also this clarification.

We’ve archived Mr. Archut’s schematic here:

Disclaimer: proceed at your own risk! We take no responsible for fried microphones or fingertips.

The M92.1S ships in a metal suitcase and includes a dedicated power supply (p/n N 920.1), power cable (p/n C 92.1), and an elastic suspension mount (p/n EA 92).

The mic has been made available in three finishes:

• satin nickel (p/n 211189)
• matte black (p/n 211190)
• 24K gold anniversary edition

As of 2010, the 24K anniversary edition is no longer made.

Note that the frequency-response graphs on the MTG website for the M 92.1 S and UM 92.1S are identical to those of the UM75, UMT70S, and MT71S, despite the wild variation in topologies, circuitry, and headbasket design among those microphones. The graph linked to below is a sample from an individual M 92.1 S and is therefore much more predictive of this mic’s performance.

The Microtech Gefell M 92.1 S is also known as: M92.1S.

Specifications

Frequency Response - CardioidClick Graph to Compare!

Pickup Patterns	Pads & Filters
Cardioid (19 mV/Pa; 40 - 18,000 Hz)

Capsule Dimensions	Impedance	SPL/Noise
Diameter n/a	200 Ohms (Low)	Max SPL: 118 dB Self-noise: 15.0 dB(A)

Weight	Length	Max Diameter	Interface(s)
430g (15.17oz)	197mm (7.76'')	42mm (1.65'')	3-pin XLR male (1)

Power Specifications
Includes tube power supply

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